Inhibitor



2oz. UUMr'USI I IUNS,

Patented July 29, 1930 UNITED STATES Examiner PATENT OFFICE GEORGE BABSKY, ORNEW YORK, N. Y., ASSIGNOB T0 AMERICAN G'YANAMID COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE INHIBITOR IoDrawing. Application filed July 2,

This invention relates to inhibitors, that is, to substances which protect steel and similar materials from corrosion by acids in the process of pickling metals.

. such as sulphuric acid, called a pickling bath, holding the solution at a predetermined temperature, usually above room temperature and immersing the steel pieces therein for a length of time suflicient to remove scale and other matter from the surface of the steel. The acid tends to attack the steel and there is added to the pickling solution a small amount of a substance, called an inhibitor. to protect the steel from attack by the acid. while still allowing the acid to act on and remove such surface material from the steel as is detrimental in the subsequent coating operation.

The present invention is intended to provide an inhibitor which is easily prepared, which is low in cost and which is highly effective in a pickling solution in very small amounts.

I have discovered that substances which might be termed broadly gldel vdgammaiic amine compounds are effective for this purpose. Among such compounds are ethyl}: dene-aniline which is formed. as is we known by the action of acetaldehyde on aniline. and toluidine-acetaldehyde. avhich is formed by the action of acetaldehyde on mixed toluidines. v

The reaction of acetaldehyde on amlme to 1929. Serial No. 375,589.

form ethylidene-aniline may be represented as followsr n CHLCHO'i'CHI-NHfiCCHLN ACHQl'HIO The generic formula for the aldehyde-aromatic amine compounds may be represented as follows:

in which R represents an aryl group and R i v represents an alkyl group.

Although I have found that substances of this character are highly efficient as inhibitors, the effectiveness thereof may be increased by certain treatments.

1. I have found that when ethylidene--' original substance.

2. I have found that ethylidene-aniline and other aldehyderaromatic amine compounds if heated with sulphur, f orexample, at about lm' crenuarefiux condenser for a substantial period of time, say about 1% hours, the resulting product isfar moreefiective than the original compound or even than the compound as treated in accordance with the procedure outlined in the above paragraph 1. The amount of sulphur may vary and I have used from 5 to 15 per cent of sulphur with excellent results. These sulphurized compounds are of indefinite structure in which the sulphur appears to be added on to the rest of the molecule, but in any event it appears that these compounds are not of the nature of thio-aldehydes since they do not The material so treated is' I nIore "effective a's"'afi inhibitor than the.-.

ibitor,

inhibiting value ng value g table g the reit will be in steel 130 y less of the inh .g

g value is very high:

of ethylidenesulphur dissolved in etone and alcohol so the inhibitor hibitin consists y of ac is 3 by weight of the proportions of alcohol and 120 and is the same amount of the 125 irable that the inhi itor ing greater than the inhibiti gent alone. In the followin nevertheless has :1 hi t which is I have shown the efiect of dissolvin give off hydrogen sulphide as do such comcontaining considerabl pounds.

The substances constituting the subjec matter of my invention were tested in a. pickof the rea 5 bath in the following manner:

pickling solution consists of 250 cc. of agent in solvents, from which 6 per cent by weight of 66 B. sulphuric acid. n ed tha the gent ance dissolved in alcohol and carty of plac Reagent Reagent B is the same substance disin the same Reagent C is the same substance dis- Reagent D llt is highly des e, in solid granular form in order to avoid .an equal quantit solution.

ylsolved solved in the same amounts of alcohol and ethylidene di-chloride same subst bon tetrachloride.

ylidenehe treataniline heated with 5 d efiect although the necess y the latter, that the rea phur added thereny increase various solvents of b was man was was e 0 0 L00 20 0 00 0 m e S s i 2. m sum .3 man man im 4 0 00 000 0 0 0 0 0 0 510 95 598 625 i s mmm mmm mmm mmm m m 0 0mm mow mmw mm a 0 0 0 0 0 0 0 00 000 P m m saw mm m ll Ii 1 W 988 00 7.8 886 02 9252 3 9 3224 4 7 l 89 e 4.4.3 3.33. 3.3.0 I Wham man ammmw mwmm wmmm momm m 90 0 456 m m 1 1 00 1100 0100 0 0 0 0 0100 0 0 0 0 0 0mm mva a? w I m 4Z3 is w 2:11 i A 36 4 24 7 14.. 5 .4 7 992m mm m t mmw awn m m mom mu .mmm wamw mmmw wmmm wmmo mmoo A as. .3. 2 2 0 0 00 0 000 0 000 000 0 0000 0000 333 443 433 333 m n m fl 72 T27 i 000 lr 39 18 27 l 53 5 m am m0m wmo mmm Mmm m 1 mmmm ammo m m4 sums men suwm am il. s 0 mm 2 2 3 3 aaaa aiaa 3 3 4.4

m h n u n m m m n u u n m mm e n S Y Q 8 O S m 54 BMSNW 4 3mm .amww WHO 8%76 789 n a d r m LL 3 047. 453 0 ofl a mvm M 3334 333 33 3 mw mrmu dnum e 10 b Eb 1 t u 6 2 07 1 T5. 0 .0 2 5. O5 7 md w m n h m a m swam nmsm mawm m1mw mmwm mama a O r m W n w m 8 s 3 3 003 4 taut 3 004 3 4 4 343 3 4.3 33 muu tma lewd l M m s m mm 0 e t n i m c e m m r a .mm P w wmum wmmm mwmm moor 0011 wmwm t.m W 0 .r ed a y mm 0 0 00 00 00 0 0 0 0 0 00.0 0 00 0 00 0 0 a dH vm m w m mu a 0 D t hQ e a u c s w n S m a e dt n a e t .1 a m u n m is ai e s w m n l n n e e a .1 s n 5 h n m tm ma... 1 a m S 3 H ihuit. de a s r t W n n B n m e d o n 2 U or O u V 6 e n t e m m 5 .1 1 at o dd a a a 5 1 8 8 .1 u. e n m m m m 1S e m m l m. m

0 y w a a ed a \.u w e e e 0 e 0 m n m g w R .n .m w m mr m m m m owm m r m yt o w 6 new 8 6 M M mm mm m m mm m m a a S t 6 o E S S W. V H .0 kn H h h enouerfln eo m 0 mm v. m m v. m. v.

8 4 0 u r fb 00 m t to m t m h h n h n tl3tfwri sioa NN E E E E Ev E 1 1 m a a 4 4 y heating alone or heatparticularl ased eflectiveness thereying amounts of phlorbenzol. y a small amount of ylidene-aniline as an initing properties of the material. hat reagents of the above From the above it is clear that eth aniline is a good inhibitor and t g with sulphur, causes greatly incre Similar effectiveness can be obtaine g the previously heat treated eth Apparentl s suflicient to give the desirable 60 crease in the amount of sul I have found t ment thereof either b in of. 55 heatin idene-aniline with var sulphur. sulphur i properties to eth to did not seem to have a on the inhib .type may be dissolved in c= organic nature and the solution 252. COMPOSITIONS, 149

.treatfid etliydidne aniline with Herdsmthe same s ubstance with soda' a'sh and anhydrous sodium sulphate (D-36). The results obtained by the use of such mixtures is shown in the following table:

llwlvents for the inhibitors or the solid arenalaif iiifi rf "prsrious scribed act in the nature of dispersing agents for-T neinhibitorg'in that they assist in inhibitor throughout the "picklingihath,.-thereby vincreasing polymerization and inhibiting activity, in accordand???thi'tl'ifefv'vell lgnown'principles' of col- IGid cEemistry. Other dispersing agents tliarithos e mentioned may, of course, be used without departing from the spirit and scope of the invention.

t Weight of metal grams W grams Per c 1055 Average Amount per cent Reagent of reagent loss in grams At start After 20 Am-ar 40 20 min 40 min 20 min. 40 min 40 min min. mm.

0.075 3. 620 3. 597 3. 570 0. 023 0.050 0. 63 1. 38 D-2T 0.075 3. 007 3. 581 3 3. 558 0. 026 0. 049 0- 72 1. 36 1.37 0.375 3. 580 3. 572 3. 563 0. 008 0.012 0.22 0.33 0.375 6 3. 426 3. 417 3. 410 0.009 0. 016 0.26 0.47 0. 40 0.100 4. 112 4. 091 j 4. 067 0.021 0. 045 0.51 1.10 0.100 3.970 3.950 3. 927 0.020 0. 043 0.50 1.10 1. 10 0.200 4.099 4. 081 i 4.005 0.018 0. 034 0.44 0.83 D-36 0.200 4. 200 4. 184 4.165 0- 016 0. 035 0.38 0. B4 0. 84

I have further tested some of the above compositions in a pickling solution at a lower temperature than given above, namely, at 158 to 160 F. Under such conditions the results obtained were somewhat better than at the higher temperature, but in either case whether at the higher or the lower temperature the inhibiting value of my compounds approaches perfection, that is, there is substantially no loss of metal due to the action of the acid in the pickling solution.

Although I have described my invention with particular emphasis upon the ethylidene-aniline compositions, and have shown that the sulphur compounds thereof are highly efi'ective as inhibitors, my invention is not limited to this class of substances as I have found that other groups of compounds of similar nature are also efiective, particularly when heated with sulphur. In producing my compositions I may use in place of aniline, toluidine, xylidene or derivatives thereof, and in place of formaldehyde or acetaldehyde, I may use substances giving similar reactions. The amounts of inhibitor used in pickling baths may of course be varied widely and the figures contained herein are to be considered as merely illustrating the small amounts which may be efi'ectively used. Although under different circumstances greater or lesser amounts might be used, I consider my invention to apply broadly to the use of aldehyde compounds of aromatic amines as such or modified by suitable treatment, and my invention is not to be limited except as set forth in the claims appended hereto.

Vhat I claim is:

l. A method of pickling metals which comprises subjecting the same to a pickling bath containing a small amount of a sulphurized aldehyde-aromatic amine compound.

2. A method of pickling metals which comprises subjecting the same to a pickling bath containing a small amount of an ethylideneaniline compound.

3. A method of pickling metals which comprises subjecting the same to a pickling bath containing a small amount of a sulphurized ethylidene-aniline compound.

4.. A method of pickling metals which comprises subjecting the same to a pickling bath containing a small amount of an ethylideneaniline compound which has been subjected to heat for a substantial period of time.

5. A method of pickling metals which comprises subjecting the same to a pickling bath containing a small amount of a solution of an ethylidene-aniline compound.

6. A method of pickling metals which comprises subjecting the same to a pickling bath containing a small amount of a solution of a sulphurized ethylidene-aniline compound.

7. A method of pickling metals which comprises subjecting the same to a pickling bath containing a small amount of a mixture of an ethylidene-aniline compound with a solid dispersing agent.

8. A method of pickling metals which comprises subjecting the same to a pickling bath containing a small amount of a mixture of a sulphurized ethylidene-aniline compound with a solid dispersing agent.

9. A method of pickling metals which comill) prises subjecting the same to a pickling bath containing a small amount of an ethylideneaniline compound previously heated with about 5% to 15% sulphur.

10. A method of pickling metals which comprises subjecting the same to a pickling bath containing a small amount of an ethylidene-aniline compound previously heated with about 5% sulphur.

11. A method of pickling metals which comprises subjecting the same to a pickling bath containing a small amount of an alde hyde-aromatic amine compound and a dispersin agent for said compound.

12. 5 method of pickling metals which comprises subjecting the same to a pickling bath containing a small amount of a sulphurized aldehyde-aromatic amine compound and a dispersing agent for said compound.

13. A method of pickling metals which comprises subjecting the same to a pickling bath containing a small amount of an ethylidene-aniline compound and a dispersing agent for said compound.

14. A method of pickling metals which comprises subjecting the same to a pickling bath containing a small amount of a sulphurized ethylidene-aniline compound and a dispersing agent for said compound.

In testimony whereof, I have hereunto subscribed my name this 25th day of June, 1929.

GEORGE BARSKY. 

